The appearance and the commercial development of mobile telephones and microwave ovens, as well as rapid growth in radio and television stations, mean that people live in an increasingly dense electromagnetic fog.
Similarly to what has happened in the x-ray protection area, the difficulty of seeing such electromagnetic waves has led to a serious requirement in society for information and protection.
The question of any incidence of mobile telephony on the health of individuals has caused much controversy over many years.
One of the difficulties concerns the measurement of specific absorption flow (SAF), or the power absorbed in watts per kilogram of living tissue. SAF measurements in vivo are naturally not possible by probes sensitive to the electric field or to temperature.
Medical magnetic resonance imagery (MRI) and numerical methods for electromagnetic calculation allow estimation of the electric and magnetic fields, but it is difficult to modelize a radiotelephone numerically (see FTRD, France Telecom, ENST models).
The calculations performed in accordance with the existing models for GSM give an SAF of 1 watt/kilogram, with 13% of this power being absorbed by the brain, 30% of the energy being absorbed in a 5 cm cube centred on the inner ear, and the maximum estimated SAF in the inner ear being of the order of 0.4 watts/kg for a power of 250 mW and at a GSM frequency of 900 MHz.
Although the SAF measurements give rise to an uncertainty level of 35%, the European national regulations make use of it, since the SAF is the only measurable physical parameter that is recognised unanimously by the technical and scientific community regarding the effects on health of the electromagnetic fields of the GSM system.
Thus, the maximum peak power authorised in France for GSM is 2 watts at 900 MHz and 1 watt at 1800 MHz, with TDMA chopping at 217 Hertz, and the maximum allowable SAF being set to 0.08 watts/kg for the public (regulation 1999/519CE) with 2 watts/kg locally per 10 grams of tissue.
By way of guidance only, a mean conductivity value of 1 S/m for tissue, at 900 MHz, gives an electric field strength of 30 V/m to get an SAF of 1 W/kg.
The electromagnetic fields associated with mobile telephony at between 850 and 1900 MHz have an apparently low thermal effect (less than 0.1 degrees).
A large number of studies have been conducted on the effects on health of these waves:                the cardiovascular system (blood pressure, heart rate),        cancers (glioma, meninglioma, neurinoma of the hearing, cancers of the parotid glands, etc.),        embryonic reproduction and development,        The immune system (IgA) and the endocrinal system (melatonin, cortisol),        cognitive functions such as memory, attention, concentration, sleep, headache, epilepsy, etc.,        hematoencephalic barrier,        thermal shock protein.        
Studies have concerned the symptoms that cannot be quantified by a physician (fatigue, sensation of heat, irritability, vertigo, etc.).
It is only with difficulty that these epidemiological studies can be affirmative regarding the impact of mobile telephony on the health of individuals, to the extent, in particular, that one cannot even consider setting up double-blind testing.
Several written articles in the popular scientific press have also suggested the potentially harmful effect of electromagnetic waves.
The major national media, especially in France, regularly raise this question, as for example in the Le Monde daily on 11 Sep. 1996, 10 Mar. 1999, 30 Jan. 2001, and 28 Mar. 2002.
A very large number of patent applications have already been submitted for devices aiming to protect users from cellular phones (see European classes H01Q1/24A1C and H04B1/38P2E).
Reference can be made, for example, to documents WO-03/005487, FR2.826.784, FR-2.781.088, WO-03/043122, and WO-2005/031918, some of which were originated by this present inventor.
The protection devices known from the prior art, such as those described in document WO-2005/031918, nevertheless have the drawback of having a very small radius of action. In fact, this ranges from a few millimeters to one centimeter only.
So there exists a need for the protection of people in relation to the waves emitted by emitters (or transmitters) within several meters, or even several tens of meters, of where people are located. This is the case, for example, of mobile telephone relay stations, which can be located close to residential areas.
The problem that then arises is therefore how to provide a device for the protection of people in relation to electromagnetic waves that have an effect over large distances of up to several tens of meters.